1. Field of the Invention
The present design relates to the projection of stereoscopic images, and in particular to reducing the effects of image leakage between left eye and right eye views, also referred to as crosstalk or “ghosting.”
2. Description of the Related Art
Stereoscopic images are created by supplying the viewer's left and right eyes with separate left and right eye images showing the same scene from respective left and right eye perspectives. This is known as plano-stereoscopic image display. The viewer fuses the left and right eye images and perceives a three dimensional view having a spatial dimension that extends into and out from the plane of the projection screen. Good quality stereoscopic images demand that the left and right eyes are presented independent images uncorrupted by any bleed-through of the other eye's image. In other words, stereoscopic selection or channel isolation must be complete. Stereoscopic selection can be accomplished to perfection using isolated individual optical paths for each eye, as in the case of a Brewster stereoscope. But when using temporal switching (shuttering) or polarization for image selection, the left channel will leak to some extent into the right eye and vice versa. The effect of this leaking is referred to as ghosting or crosstalk.
Various designers have attempted to reduce crosstalk or the ghosting artifact in stereoscopic displays. Most notably, Levy, in U.S. Pat. Nos. 4,266,240, 4,287,528, and 4,517,592, lays out the basic technology for subtracting a portion of one image from the other to reduce the ghosting effect. Levy's implementations were directed to stereoscopic television systems. Ensuing solutions draw heavily on Levy's work and add relatively small improvements.
In the motion picture realm, many degrading artifacts have been cited in the literature as detracting from the enjoyment of the projected plano-stereoscopic motion picture experience, including the breakdown of convergence and accommodation, unequal field illumination, and lack of geometric congruence. None of these artifacts are more important than leakage between left eye and right eye images. Stereoscopic movies show deep, vivid images that create a significant, realistic perception of a spatial dimension that extends into and out from the plane of the projection screen, and this effect is most degraded by crosstalk.
Certain solutions have been proposed to address ghosting, but many of the proposed solutions tend to be uniform across an image or screen surface, i.e. remove the same ghosting artifacts in the same way regardless of screen position, environment, or any other pertinent factor.
The present design seeks to address the issue of ghosting or crosstalk in a projected plano-stereoscopic motion picture environment. It would be advantageous to offer a design that enhances or improves the display of projected plano-stereoscopic motion pictures or images by reducing the crosstalk associated with such motion picture or image displays over designs previously made available.